This high-end S10 proposal requests funds to purchase a Zeiss LSM780 NLO multiphoton/single-photon confocal microscope coupled to a broad tuning femtosecond laser from Newport/Spectra-Physics (the Insight laser). The instrument will be housed in the Cornell Biotechnology Resource Center's (BRC) Imaging Core facility in the basement of Weill Hall on the Ithaca campus of Cornell University. The goal is to provide a modern, user-friendly combined nonlinear and confocal fluorescence imaging system for use by ten NIH-funded major users and 6 minor users located on the Cornell campus. The instrument will replace an outdated Bio-Rad 1024 multiphoton system which was installed originally in 1996 in the P41 Developmental Resource (DRBIO) in collaboration with Bio-Rad, the initial licensee of multiphoton microscopy. The instrument was later taken over by the Cornell Biotechnology Resource Center (BRC) imaging facility which serves the entire campus. It has been retrofitted numerous times, but still runs under the defunct IBM OS/2 operating system and the Bio-Rad LaserSharp software package rendering it completely un-supportable. Acquisition of the state-of-art system requested will greatly advance the capabilities of the Cornell Imaging facility, and allow us to better serve the needs of our NIH funded researchers. This instrument will not only be replacing an unsupportable 16 year old multiphoton microscope, but will be adding several new previously unavailable features that will be of great benefit to our users. These include two-photon excitation wavelengths up to 1300 nm that will provide for deeper imaging with higher viability, and, for the first time, allow our users to assess families o red dyes and fluorescent proteins that are currently inaccessible with our standard Ti:Sapphire source. The system also has the most up-to-date highest quantum efficiency detectors - both in the confocal head and the external non-descanned detector system. All of the users of this proposed microscope will be imaging live animals, tissues or tissue preparations and all will benefit from the 2 to 3 fold increase in fluorescence detection these newer photodetectors provide. Equally important, the Zeiss system and Zen software provide extremely precise control of the laser excitation as required by our users who have a need for 3D localized photoactivation, photobleaching and targeted photoablation. The requested instrument is specifically tailored to the needs of our NIH funded major and minor users, and will provide for their fluorescence imaging needs well into the future.